The Bossier banner. [volume] (Bellevue, Bossier Parish, La.) 1859-1952, 1887-04-28

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lamp viii ignite gas outside it if ex-
posed to an explosive current travelling
at less than four hundred feet per min
ute 81 nkag YvxKg
The Royal Commissioners, as far back
as 1880, directed the attention of the
Home Secretary to the fact ssthat the
employment of the ordinary Davy lamp
without shield of metal or of glass. in
an explosive mixture, when the air
currents exceed six feet per second, is
attended with risk OF. accident almost
amounting to certainty" Indeed,
merely attempting to blow out the
flame within the lamp may cause it to
ignite an inflammable mixture Happily
invention has not been long behind
necessity, and there are at least half-a-
dozen forms of lamp which are safe
under current velocities exceeding three
thousand feet per minute. Everybody
will agree with the conclusion of the
Royal Commissioners that whilst it
would be unwise to make particular
lamp compulsory on the ground that
difficulties might thereby be thrown in
the way of introducing improvements
in future, it is nevertheless. desirable
that some control should be exercised in
reference to the kind of lamps to be en-
ployed ineoal-mines, and that only those
lamps should be used which are author
lied from time to time by the Secretary
Of State. sass# s9s - " a 81
Fire-damp, however,zis not the most
formidable of the causes of colliery
explosions. 1t is IA doubtful, indeed,
whether a single one, of the more dis
astrous explosions Of modern times can
be directly and wholly attributed to its
action. 1t is significant that violent
explosions seldom occur nowadays in
very wet pits, although the air in them
frequently contains fire-damp. More
over, when explosions do occur in such
pits they rarely extend over large
area, and the loss. O. life from them is
comparatively small Such catastro-
phes as those of Aberearne. Risca,
Seaham and Penygraig, where
hundreds > of men and boys are
killed. and where evidence of the ex-
plosion is to be met with in nearly all
parts of the pits. almost invariably
happen in dry. and dusty pits, 1t hardly
admits of question that explosions of
this kind are dependent upon the pres
ence of this dust Dust explosions in
flour-mills have long been known, but
it is only within the last few years that
the action of finely divided coal-dust in
initiating or propagating a. .colliery ex-
plosion has received much attention.
The atmosphere of deep dry mine is
always impregnated with more or less
dust. 1t settles everywhere, not only in
the working places, but in the intake
and haulage roads, 1t is not only on
the floor, but hangs from the roof
and timbers, and is heaped up on the
ledges. A violent movement of the air
dislodges it in clouds; if a naked flame
be introduced into such cloud it in
flames with explosive violence and the
conclusion of air is followed by fresh
clouds Of dust through which the flame
is propagated.
.-the smutty grain
With sudden blaze diffus'd infiames the air.
Milton said this of gunpowder; it is
even truer of coal-dust.
Now there are many conditions in the
ordinary working of a coal mine which
NAV occasion these violent movements
of the air. and chief among them is
the prevalence of what is techni-
cally known as s.shot-iring g''-that is,
blasting by means of gunpowder. Gun
powder is used in the mine either for
bringing down the coal or for removing
stone, in order, for example, to make
roads for the passage of horses, and for
engine planes, etc. A hole is driven or
drilled into the coal or stone, into
which certain quantity of powder, to-
gether with fuse, is introduced, and
the rest Of the hole is ''stemmed" or
..tamped that is, filled up with small
stones and earth or, too frequently,
with small coal itself. The fuse is ig-
nited and the workmen retire either i'm
to refuge hole" or round a corner
until the blast is made, Occasionally
it happens when the, charge OF gun
powder is too large, or when it is inn
perfectly stemmed. or when the rock is
unusually hard, that the powder blows
out the stemming and there is violent
conclusion of air, and from the mouth
of the tlriu-hole there issues a flame
the length Of which viii be greatly
| increased if small coal has been
used in the stenaming. Indeed, it is
not necessary for the shot to be "blown
OUT to produce either the flame or q
concussion of air sufficient to dislodge
the inilammable dust. We have here a
condition Of things which may be high.
ly dangerous in dusty pits. 1t has been
proved over and over again that shot
firing has been the immediate precursor
of some of the most disastrous colliery
explosions on record. The influence oi
dust in at least propagating an explosion
is now generally recognized by mining
engineers and colliery managers, but